The Series 2 TiVo boxes cannot accept HD signals, but they will work with FiOS SD channels. I think the Series 2 boxes accept CableCards so you don't necessarily need a Verizon set-top box, but CableCards are not compatible with On-Demand services. If you have an HDTV and want HD channels, you'll need a Series 3 or TiVo HD box.
Thanks, that is what I wanted to know. Dont' care about HD yet cause I dont' have an HD TV. My main thing is I dont' want 2 stb's.